Metrics

Runix collects per-process and system-wide resource metrics.

Implementation

Located at internal/metrics/:

File	Responsibility
collector.go	Collector — periodic per-process metric collection via /proc
system.go	GetSystemMetrics() — system-wide memory, CPU load, uptime
prometheus.go	WritePrometheus() — Prometheus text exposition format output

Per-Process Metrics

The Collector periodically reads /proc/[pid]/stat for each tracked process:

Metric	Source	Description
pid	Tracking	OS process ID
cpu_percent	/proc/[pid]/stat fields 14-15	CPU usage percentage
mem_bytes	/proc/[pid]/stat field 24 (RSS)	Resident memory in bytes
mem_percent	Computed	Memory as percentage of total
threads	/proc/[pid]/stat field 20	Thread count
fds	/proc/[pid]/fd/	Open file descriptor count
collected_at	Timestamp	When metrics were collected

Collection Flow

1. Collector.Start(interval) begins a goroutine that ticks at the given interval
2. On each tick, collectAll() reads metrics for all tracked PIDs
3. Results are stored in a mutex-protected map
4. Callers use Get(pid) or GetAll() to read the latest values

Tracking

• Track(pid) — Add a PID to the tracking set
• Untrack(pid) — Remove a PID from the tracking set

System Metrics

GetSystemMetrics() reads system-wide metrics from /proc:

Metric	Source
total_memory	/proc/meminfo → MemTotal
free_memory	/proc/meminfo → MemAvailable
used_memory	Computed: total - free
cpu_load_1	/proc/loadavg field 1
cpu_load_5	/proc/loadavg field 2
cpu_load_15	/proc/loadavg field 3
uptime_seconds	/proc/uptime field 1
process_count	/proc/loadavg field 4

Prometheus Format

WritePrometheus() outputs metrics in Prometheus text exposition format:

# HELP runix_process_count Number of processes by state.
# TYPE runix_process_count gauge
runix_process_count{state="running"} 3
runix_process_count{state="stopped"} 1

runix_process_restarts_total{name="api",namespace="default"} 0
runix_process_restarts_total{name="worker",namespace="default"} 2

runix_process_uptime_seconds{name="api",namespace="default"} 3600
runix_process_memory_bytes{name="api",namespace="default"} 47185920
runix_process_cpu_percent{name="api",namespace="default"} 2.30

runix_process_count_total 4

Platform Support

Platform	Support
Linux	Full — reads /proc filesystem
macOS	Not supported — returns empty metrics
Windows	Not supported — returns empty metrics

The collector checks runtime.GOOS and returns zero-value metrics on non-Linux platforms.

What's Next

• Status Command — Displays CPU and memory per process
• Web UI — Dashboard with live metrics